DOUBLE-PULSE TECHNIQUE FOR THE EVALUATION OF THE SATURATION PARAMETER IN SINGLE-SHOT LASER-INDUCED FLUORESCENCE MEASUREMENTS - AN APPLICATION TO LEAD IN A FLAME

The enlargement of the probe volume in saturated laser induced fluorescence measurement is a considerable drawback for absolute concentration measurements. For practical purposes, a double pulse technique was developed allowing determination of the saturation parameter, which has a major influence on the probe volume enlargement. The technique is based on the detection of the fluorescence produced by two time-delayed laser pulses of different intensity. The basic theory of the technique is presented, together with the results of an experimental application to Pb in an acetylene/air flame. The implications for absolute concentration measurements are also discussed.